Preparation of uranium bromide



Patented July 24, 1951 UNITED TAT-ES PATEN 'oFFIcE PREPARATION or URANIUM BROMIDE T 7 Jack E. Powell, Ames, Iowa, assignor to the United States of Americaas represented by the United States Atomic EnergyGommission No Drawing. 'A'pplicati o'n: May 1, 1946, Serial No. 666,531

@This invention is concerned with the produc-. tion of uranium-bromine compounds such as UB1; or UOBrz. It is frequently advantageous to produce a compound such as UBr4 from a source material such as the uranium oxide, U02. This is advantageous for the reason that U02 may be prepared in a relatively pure form and therefore production of the uranium-bromine compounds in a relatively pure state is simplified. The problem of preparing uranium tetrabromide from U02 is complicated, however, since bromine does not react readil with U02.

In accordance with the present invention it has been found that the compounds UBM and UOBI'z may be prepared'by reacting the compound UO2-2US2 with a brominating agent such as bromine. Since UO2-2US2 may be prepared conveniently by reacting U02 with carbon disulphide the present invention provides a convenient process whereby uranium tetrabromide may -be prepared from U02 in a simple manner. The accomplishment of the foregoing and the production of the novel compositionsformed in theabove described process constitute some of the principal objects of the invention. Other objects will become apparent by reference to the following more detailed disclosure.

:As herein contemplated, the production of UBr from UOBIz may be accomplished in a series of stages. Thus the uranium oxide may be reacted with carbon disulphide in accordance with the following equation:

The above reaction may be conducted by heating UOzor U303 to a temperature of about 800 to 1000" C. or above and passing over the oxide or through it a mixture of gaseous carbon disulphide and nitrogen. The resulting compound UO2-2USz is a solid and remains in the reactor while the carbon dioxide which is evolved is removed.

Following preparation ofthe uranium oxideuranium sulphide compound above-mentioned, this compound may be brominated by suitable methods such as by passing gaseous bromine through or over a bed or layer of the UOz-ZUSz. It is found advantageous to conduct this reaction in the substantial absence of air and the reaction proceeds apparently in accordance with the following equation:

This bromination reaction may be conducted in any suitable inert reactor which is capable oi 8 Claims. (Cl. 23.14.5)

resisting the action'of bromine or the various re-'- action products. When the process isconducted on a small scale, quartz reactors are suitable. The reactor should be provided with a suitable condenser system usually air-cooled, adequate inlets for introduction of the brominating agents and outlets for conduction of the evolved gases through the condenser system. Adequate means for heating the reactor to the required'temperature should also be provided.

The bromination'described above may be con-' ducted at an elevatedtemperature, usually above about 200 C. When the process is conducted at temperatures below about 600 0., uranium tetrabromide is formed in solid state and largely remains in the reactor, only slight amounts subliming and being collected in the condenser system. In such a case it is generaly advantageous to raise the temperature of the reactor after bromination is substantially completed, to a temperature above about 600 C. whereby the UBr4 formed sublimes and is collected in the condenser. When this subliming process is conducted at a temperature of about 600 to 700 C. the compound UOBRz remains behind. This compound (uranous oxybromide) is generally in the form of greenish yellow needles or a fine yellow to tan powder. It is relatively air stable and nonhygroscopic and dissolves readily in water to givea clear green solution which darkens gradually upon standing.-

The uranous oxybromide may be disproportionated into U02 and IBM approximately in accordance with the following equation:

This process may be effected by heating the UOBlz at a temperature of 800 to 1000 C. or above but'below the decomposition temperature of UBr4. In such acase the UBn sublimes and is collected in the condenser while the uranium oxide remains behind. .-This residue of U02 may be recycled for the formation of further uraniumbromine compounds in accordance with the above-described process.

The process is capable of a number of variations. For example, the bromination of UOz-ZUSz and the decomposition of the resultant UOBrz may be conducted simultaneously by conducting the bromination at a temperature above about 800 C. and in such a case the resulting UBm is sublimed and collected in a suitable condenser system. Alternatively, all of the reactions represented by the above equations (1), (2), and (3) may be conducted simultaneously be the most effective brominating agent for this purpose other brominating agents such as may be used.

The following example isfgil'lustrativei 1 A quantity of U02 which had -,be en ,previous purified and is substantially free from impirri;

ties was placed in a quartz reactor in a, furnace and thereactor was provided with an inlet for introducing carbon disulphide into the bed of UO2."1':'I[ 118 :reactor was "also-provided with an outlet connected to an :air-co'oled condenser i sys-x tem'zfor collecting lUB14 which wasto y be formed. A carbon disulphide-nitrogen cgaseous I mixture was' passed through the uraniumoxide-bed while heating the .oxide' to approximately-800 ,to 1000? C; andthe reaction was continued until carbon disulphide'rceas'ed to' be .taken up bythereaction' mixture. Thereafterythe UO: w 2.US2 :obtained was heated to about 4t'10-:.-*C. and astream of bromide and nitrogen formed :bygbubbling nitrogen through liquid bromine was passed through the resulting bed of U2--2US2.-' Introduction of bromine was continued?until-formation -Of,'SzB12 and distillation of -this:arraterial from the reaction. mixture ceased. Thereafter, the tempera:- ture oft'he reactor was raised toabout650 to 700 Clw-and UBridistilled from the mass.= This' UBr4 was-collected in the condenser. -When distillation of IUBI'Q ceased the temperature :of the reaction mixture in the reactor iwassrai'sed about 800 to 1000"C. whereupon'furth'er UBri'sublimed from *the mixture' due 'to*- decomposition *of .the

uranous- *oxybromide. This heatingwas -:con-

tinued until "no *further amountiof UBM- WES.

subli'rned. "The remaining uranium ox'ide (U02) was left :in 'the reactor and used with"further additional quantities of uranium eoxide to pro duce an additional amount of uranium "tetrabroand UOBrz which comprises brominating 4 CS2 and a brominating agent to form C02, a volatile sulfur-containin material, and a mixture of UBrr and UOBrz, and removing said C02 and said volatile sulfur-containing material from the mixture of U312 and UOBrz.

3. A method of preparing UBr4 which comprises reacting U02 with-f CS2" and a bioininating 'agent at a temperature of atlea'st 600' 0., dis- 4. A method of preparing UBr4 which com- \prises reacting-U02 with CS2 and a brominating agent at a temperature above about 800 C. =UBr4 therefrom, and collecting the 5. method of preparing a mixture of UBn to form said mixture and a volatile sulfur-containing material, and removing said volatile materi'alfrom the resultant mixture of- UBrvand U0Br2. GHA method of preparing-afmixture of U31; and UOBrz which comprises reacting U02 with CS2 to form *U02- 2US2,, 'brominatin'g said U02-2US2 to form a mixture' of UOBr2 and UB1; and a volatilesulfur-containing material, and re moving saidvolatile material fromthe mixture of UBr4 and UOBr2. I

7. A method of preparing \UBI4 which -'com-.'- prisesreaeting U02 with CS2 to form U0z-2USa. brominating said UO2'-2US2"to form a mixture of UBr-iand U0Br2 and a 'volatile sulfur-containing material, removing said volatile material from said mixture of 'UBri 'and U0-Br2, cheating said mixture to a temperature of above "700 .C., distilling UBr4 therefrom, and collecting the UB1'4.

8'. A method of preparing UBrr which comprises reacting U02 with CS2'-to form UOz-2US:, brominating said UO2-j2US2 to form a volatile sulfur-containing material and a mixture 'of UBri and "UO'Br2, removing said volatile material from said mixture, heating the mixture of UB'ri and UOBrz above about 700 C. to form UBn and U02 from said UO-Bri, distilling UBri-therefrom, collecting the'UBr i, and recycling the U0: formed in said heating of the mixture of UIBr and UOBrz. JACK E. POWELL.

REFERENCES CITED The following references are of record in the file of this patent: 

1. A METHOD OF PREPARING UBR4 WHICH COMPRISES HEATING UOBR2 ABOVE ABOUT 700* C., DISTILLING UBR4 THEREFROM AND COLLECTING THE UBR4.
 7. A METHOD OF PREPARING UBR4 WHICH COMPRISES REACTING UO2 WITH CS2 TO FORM UO2 2US2, BROMINATING SAID UO2 2US2 TO FORM A MIXTURE OF UBR4 AND UOBR2 AND A VOLATILE SULFUR-CONTAINING MATERIAL, REMOVING SAID VOLATILE MATERIAL FROM SAID MIXTURE OF UB4 AND UOBR2, HEATING SAID MIXTURE TO A TEMPERATURE OF ABOVE 700* C., DISTILLING UBR4 THEREFROM, AND COLLECTING THE UBR4. 